Automatic underfeed furnace



Nov. 5, 1935. c. D. GILPIN AUTOMATIC UNDERFEED FURNACE Filed Jan. 9, 1931 3 Sheets-Sheet 1 INVENTOR I BYM J/b ATTORNEY 3935,, c. D. GILPlN AUTOMATIC UNDERFEED FURNACE 3 Sheets-Sheet 2 Filed Jan.

ll .llllllJ INVENTOR MOM BY' ATTORNEY Nov. 5, 1935. c. D. GILPIN AUTOMATIC UNDERFEED FURNACE Fi led Jan. 9, 1951 s Sheets-Sheet 5 WIIIIIIIIIIII/ hatented Nov. 5, 1%35 AUTOMATHC UNDERFEED FURNAGE Clinton D. Gilpin, Westfield, N. 3., half to Theodore R. Harvey,

"n of one- We tfield, N. 5.

' Application January 9, 1931, Serial No. 5@7,55 2 Claims. ((Cl. lit-=) The improvements relate primarily to apparatus for automatically feeding and consuming solid fuel in a finely divided state for the purpose of generating heat for steam, water or hot air, domestic or other heating, but may be applied to any use to which it can be adapted. The objects of the improvements, among others, are to provide better means and methods for the feeding and consumption of such fuel and discharging the solid products of the combustion and controlling the same manually and under the influence of thermally. operated regulating devices, and also to render the apparatus more simple, durable and dependable, as well as more certain and efficient in operation. Other objects and advantages will be apparent to those skilled in the art.

The improvements are illustrated in the accompanying drawings, in which- Fig. 1 is a general side view in perspective of an apparatus embodying the improvements;

Fig. 2 is a similar and enlarged view of the fuel hopper and worm feed housing in position reversed with respect to the position of Fig. 1;

Fig. 3 is a medial vertical section of the parts shown in Fig. 2, on the same scale Fig. 4 is a view similar to that of Fig. 1 showing the fuel and air regulating lever and adjacent,

connected parts detached;

Fig. 5 is an'enlarged detail of the clamping block for the regulating lever with its pointer;

Fig. 6 is an enlarged vertical medial section' of the fire pot and adjacent parts, the fire pot proper being shown in side elevation with lower part broken away and the fuel feeding worm in side elevation;

Fig. 7 is a plan showing a fragment of the perforated sheetmetal fire pot in full size;

Fig. 8 is an enlarged front view of the ash pan! Fig. 9 is an enlarged perspective side view of the gear box, broken away to expose the power transmitting and motion converting and controlling devices housed therein;

a Fig. 10 is an enlarged detail adjusting means; and

Fig. 11 is a detail side view, partly broken away showing the pawl and ratchet device for operating the feed worm and the means for adjusting said device.

The fire pot I has the form of an inverted truncated cone with concave sides, and is made of sheet metal or its substantial equivalent. It receives the fuel at its contracted bottom, provides for the consumption of such. fuel while of the air damper passing up therethrough and permits the ashes to discharge over the periphery of its flared top and over the cast, fiat, marginal, annular rim 2 down into the bottom ash pan 3. This fire pot is provided throughout with numerous small perforations 4 of uniform size and evenly distributed. The size and arrangement of these perforations is important, since they are designed to prevent the fuel from escaping therethrough, and to furnish numerous small jets of air thereto to insure uniform and complete consumption of said fuel. It has been found that perforations 5 g inch in size disposed on 3 inch centers give excellent results with anthracite coal of the buckwheat, rice and barley grades. This provides approximately thirty perforations per square inch, and while it is possible to obtain satisfactory results, depending upon the size and character of the fuel and other conditions, with the fuel named, this formula should not be materially departed from. It has also been found that the size and distribution of the perforations has a direct relation to the character and quality of the combustion, and the life of the metal, as well as the conduct of the fuel. The shape of the fire pot is also important, and it has been found that it should not increase-in diameter upwardly, or flare, at a rate greater than 100 per cent, for a distance equal to its smallest diameter to give the best results.

The fire pot l is'mounted by having its rim secured between the stepped inner edge of the annulus 2 and the flanged upper edge of the outer shell 5 of the housing, and its bottom edge is supported in the annular mouth of the inner housing 8, resting on a ledge 8' thereof. The outer housing 5 provides an air chamber surrounding the flrt pet from which air under pressure of the fan or blower is supplied to the perforations 4i, and the inner housing forms a channel through which the fuel passes under pressure caused by the worm conveyor up into the firt pot. It will be seen that this fuel is forced upwardly and spreads laterally as it is consumed, and that it has a tendency to form a fiat cone with its apex above the top of the fire pot, which will cause the ashes to gravitate laterally in all directions and be discharged over the flat brim 2. It will also be seen that as the fuel approaches the top of the fire pot, it receives an increased supply of air, so that the combustion is more intense at the upper part of the fire pot and the combustible portion of the fuel will be completely consumed before passing therefrom.

In order to direct the ashes spilling over the ring 2 into the ash pan 3 in the bottom of the furnace, deflecting guides 1 on each side thereof are-provided. These guides are mounted on an annular rib with vertical face 5' of the housing 5 by means of a collar 8 extending around this rib and clamped thereon, and extensible arms 9 connecting said collar with the deflectors. In this manner provision is made whereby the deflectors may be adjusted circumferentially of the fire pot and also radially so as to accommodate them to different furnaces and to the position of the feeding worm, which may be arranged to enter through either side or the back of the fur.- nace. By this provision, the front of the furnace may be left free of all obstruction, so that the ash pan may be inserted and removed through the door of the ash pit and access to the burner had through the usual fire door. When the fuel conduit enters through the side of the furnace, one of the deflectors 1 is provided with a cut out portion 1' which will enable it to straddle the fuel and air conduits.

The fuel feeding worm I0 is mounted on a shaft H and held thereon by means of a conical nut l2 at its inner end, while the outer end is coupled to the shaft by a collar [4 keyed on said shaft and having lugs 14' entering notches in the end of the last worm sleeve section I5". The worm is laminated or made in sections, each section mounted on a short sleeve l5, engaging adjacent sleeves for rotation by means of steps l5.

The worm operates in a fuel conduit l6 having one end fitted into the tail 6" of the casting 8 and the opposite end in the ring flanges I1" of the hopper l1. Surrounding this fuel conduit is an air duct 20, fitted into the annular tail end 8" of the casting 5. The fuel conduit enters this air duct at its bend 20', and the duct then proceeds rearwardly to the blower 2|, which may be of the Buffalo forge or other suitable and well'known type, by which air is forced through the duct and into the annular air chamber 22 surrounding the fire pot.

The hopper I1 is secured to the bottom of the bin I8 by means of a top flange l1 on the hopper and a bottom flange l8 on the bin, which are secured together, fuel stored in the bin passing through the bottom thereof into the top of the hopper and surrounding the rear end of the worm III, by which it is forced forwardly out of the hopper through the fuel conduit and to the firepot. The hopper is also provided with mangets l9 extending through its walls on both sides and projecting into proximity to the worm, so that pieces of metal, such as nails and wire fragments, descending into the hopper will be caught thereby and held. The purpose of these magnets is to protect the worm against pieces of metal, which would otherwise at times be forced into the fuel conduit by the worm and cause damage. Such pieces of metal may be removed, when the bin is empty by disconnecting it from the hopper and raising it slightly to give access to the magnets, or, if desired, a door may be provided in the side of the bin or the hopper for that purpose.

The worm and blower are operated by the motor 23 mounted with said blower and the worm shaft on the base 24, the blower being connected with the motor shaft 25 direct and the shaft through a chain of mechanism about to be described. On this base is also mounted an oiltight gear box 28, through which the motor shaft extends to the blower. The mounting of the motor, gear box and blower on a common base of these elements v is an advantageous and important construction.

The mechanism through which the fuel worm is operated from the motor shaft is as follows:

The motor shaft is provided with a worm 21 5 about midway of the gear box, and this worm meshes with a large gear 28 rotating on the bearing collar 29' on the sleeve 29, on the shaft H,- and with which the said shaft rotates, being connected therewith by a locking collar 28" and a 10 shear pin 3| driven through apertures in both. The gear 28 has fixed to it an eccentric 32, and this eccentric operates in a round recess 33 in a sliding block 34, so thatas the gear 28 rotates this sliding block is given a combined vertically l6 reciprocating and swinging movement in the way 35 of the frame 36- pivoted at 31 in the bottom of the gear box.

An elliptical slot 38' in the frame 38 permits it to have the described movement on the shaft 20.

ll extending through it. This movement of the frame 36 produces a rocking movement of the arms 31, 38, through the spindle 38 extending therethrough and having its projecting end in the recess 36" in the top of the frame 38, and pro- 23 vided with an anti friction collar 38. The arms are pivoted loosely on the sleeve 28 surrounding the shaft vI I, so that they will rock thereon, independent of any movement of the shaft and without moving the shaft.

On the spindle 38 the lozenge shaped pawl 48 is pivoted, and it is pressed into contact with the teeth 4| of the ratchet 42 by an expansion spring 43 connected with its outer end and with the bar 44 mounted between the extremities of 35 the arms 31, 38. This ratchet is keyed to the shaft ll, through sleeve 28, and by it the shaft and the fuel feeding worm are rotated step by step. It will be seen that when the arms oscillate the pawl engages a tooth of the ratchet 4 androtates it as many degrees as the arc of the swing of the arms from the point of engagement to the end of that swing.

In order to vary the speed of rotation of the ratchet and the feed worm, the ratchet 42 is provided with a cover or jacket 45, rotatably mounted on the sleeve 23 and having a segment at its periphery cut away, as shown at 46, one edge of the peripheral part of the said jacket being near the position of the pawl when it is at the limit of its backward movement and when a maximum movement of the ratchet is to be produced, but being movable forward from said position by the rotation of the jacket or cover 45 to positions over the teethwhich would otherwise be engaged by the ratchet, so that the said peripheral part of the cover is interposed between the pawl and one or more of the teeth. In this manner the point at which the pawl. will engage the ratchet is varied, the pawl sliding over the periphery of the cover on going forward and until it passes the edge, and sliding over the same on its return movement. It will be apparent, however, that a friction device may be substituted for the pawlv and ratchet, if desired, or found more eflective.

Movement of the cover 45, and resulting variation in the movement of the feed warm on each stroke of the pawl is effected through the link 41 pivotally attached to the outside of the cover, at its lower end, and with the outer end of an arm 48 oscillated vertically-by a small rock shaft 49, to which the opposite end of the lever is fixed. The link 41 is jointed near its upper end and provided with an expansion spring 38 strung on the two parts of the link and surrounding the overlapping portions thereof, so that when the arm 40 moves upward while the pawl is in en'- gagement with a tooth of the ratchet, to move the cover 45 forward. and the cover is stopped by the 5 ratchet, the spring will expand and hold the link and the cover under tension, until the ratchet haspassed beyond the limit of the cover movement and move the cover to position bepose of ensuring against injury to the parts involved if the cover is adjusted while the motor is not running and the pawl is engaged with a ratchet tooth.

The rock shaft 49 is moved by the regulating lever secured thereto and for which the shaft provides a fulcrum. The shaft itself is pivoted in the side of the gear box 25 through which it passes, the aperture in the box being provided with an oil-tight packing 52. All apertures in the gear box are made oil-tight, so that it may be maintained filled with oil for the lubrication of the parts operating therein. The regulating lever 5| is operated from its rear end manually, or by means of a thermostat or similar device, and at the that end (see Fig. 4) it has an eye 5| by which it may be connected with such a device for operation. Between its pivot or fulcrum and its rear end it has a clamp, operated by a thumb nut 53 threaded on a screw bolt 54 fixed to the small block 55 and extending through an arcuate slot 56 in the plate 56 secured to the rear side of the gear box 25 at one edge, by -means of its flange 51. In this manner, the regulating arm may be secured at any desired point along the slot. The position of the arm, and the resulting speed of the feed worm, is indicated on the scale 58 by the pointer 59. The lever, however, may be left free for thermostatic operation by unclamping it and permitting the block to swing by gravity to vertical position on its loose pivot 54, or removing these parts. The movement of the lever may be limited at all times by the adjusting screws 60, 6|, threaded through apertures in ears 52. projecting from the plate 55v and, provided with retracting and locking springs 63. This enables the operator to limit the movement of the arm manually or thermostatically, with weather or other conditions in view, so as to ensure a limit to the maximum or minimum variation of the fuel supply and air forsupporting combustion.

At the forward end of the control lever 5| a depending rod 65 is secured, and this rod is the rod. To this block 69 is secured a link 10 onnected to the pivot ll of the damper I2 in heair duct 20, so that when the forward end I the regulating lever 5| is raised or lowered, e damper is opened or closed. A permanent hind the ratchet. This provision is for the puran imperforate rim surrounding adjustment of the damper on its pivot for'diiferent grades of fuel is provided in the clamp, wing nut 13 and collar 14 (see Fig. 10) and pointer 15, keyed on the damper, for the scale 16. By releasing the collar the damper may be moved, 5

by its indicator, on its pivot to difierent positions and then clamped to its pivot again by clamping the collar. By this means the position of the damper may be adjusted for different fuels, by limiting the extent to which it can be opened 1 or closed by the link 10.

The fire pot is preferably made of a high heat resisting steel alloy, such as the well known nickel-chromium alloys, and may be pressed or drawn into the form shown. Other metal, how- 15 ever, may be used, and it has been found that the numerous small perforations distributed throughout the fire pot will admit air in such a manner that the shell is kept at a relatively low temperature. This temperature is governed largely by the pressure and rate of air inflow through the perfortions, which, in relation to the rate of fuel supply also determines the volume and rate of combustion.

I claim:

1. In combination with means for feeding solid fuel in a finely divided state to and upwardly through a fire pot, a fire pot, a casing surrounding said fire pot, and means for supplying air under pressure around the outside of said fire pot, said fire pot having a contracted lower portion and an upwardly and outwardly flaring upper portion of relatively thin sheet metal composed of steel alloy, an ash receptacle beneath the same and ash deflectors converging toward said receptacle supported on said casing and mounted for radial and' circumferential adjustment thereon.

2. In an apparatus of the character described,

a fire pot in the form of an inverted truncated 4o cone having numerous small air inlets therein,

the upper periphery of said fire pot, a casing surrounding said fire pot and spaced therefrom to provide an air chamber surrounding. the same, means for forcing solid fuel in a finely divided state into the lower part of and up through said flre pot, means for supplying air under pressure to the exterior of said fire pot for said air inlets, deflectors spaced laterally from said rim and extending downwardly therefrom on convergent lines and an ash receptacle below the said deflectors and extending beyond the same, whereby the unconsumed fuel is forced upwardly beyond the top of said fire pot by the fuel pressure from below and is permitted to gravitate over said rim to the ash receptacle and is directed into said receptacle by said deflectors, said deflectors being mounted for radial and circumferential adjustment with respect to said fire pot. 30

CLINTON D. GILPIN. 

